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    <script>
        // 2. 给你一个数组["a"，“b”, "c", "d", "a", "m", "c", "d", "b", "c"];

        // 求出数组中每个元素出现的次数

        
        function lengthRepeat(arr){
            let obj = {}
            for(let i = 0; i < arr.length; i++){
                obj[arr[i]] = obj[arr[i]] + 1 || 1
            }
            return obj

        }


        let arr = ["a","b", "c", "d", "a", "m", "c", "d", "b", "c"]


        console.log(lengthRepeat(arr));

    </script>
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